Question: What is the greatest common factor of $10$ and $30$ ? Another way to say this is: $\operatorname{gcf}(10, 30) = {?}$
The greatest common factor is the largest number that is a factor of both $10$ and $30$ The factors of $10$ are $1$ $2$ $5$ , and $10$ The factors of $30$ are $1$ $2$ $3$ $5$ $6$ $10$ $15$ , and $30$ Thus, the greatest common factor of $10$ and $30$ is $10$. $\operatorname{gcf}(10, 30) = 10$